Lots of factors are at play here
- What is the PR of the forum or blog
- How may outbound links are present
- What status does the search engine apply to the forum/blog - ie. is it spammy?
I'm sure there are others.
I have a doubt which i need cleared. Not considering the PageRank, do you think it makes a difference in having a backlink(do-follow i.e.) either in forum signatures or in blog comments??
Do both serve the same in SEO or one of them is better?? Clarifying again, 'not considering the PR' or 'both of them having the same PR'.
Both are probably equal, depends on a lot of factors tbh.